2636521011661 has 2 divisors, whose sum is σ = 2636521011662. Its totient is φ = 2636521011660.

The previous prime is 2636521011617. The next prime is 2636521011671. The reversal of 2636521011661 is 1661101256362.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2581385275561 + 55135736100 = 1606669^2 + 234810^2 .

It is a cyclic number.

It is not a de Polignac number, because 2636521011661 - 2⁹ = 2636521011149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2636521011671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1318260505830 + 1318260505831.

It is an arithmetic number, because the mean of its divisors is an integer number (1318260505831).

Almost surely, 2^{2636521011661} is an apocalyptic number.

It is an amenable number.

2636521011661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2636521011661 is an equidigital number, since it uses as much as digits as its factorization.

2636521011661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 40.

The spelling of 2636521011661 in words is "two trillion, six hundred thirty-six billion, five hundred twenty-one million, eleven thousand, six hundred sixty-one".